U.S. patent application number 15/325622 was filed with the patent office on 2017-07-06 for apparatus and method for measuring residual torsions.
This patent application is currently assigned to NV Bekaert SA. The applicant listed for this patent is NV Bekaert SA. Invention is credited to Ghislain DOORNAERT, Tom GOMMERS, Lei GU, Wei SHEN, Bart VANLANDEGHEM, Erwin VEREECKEN, Tiehong YANG, Zhigao YU, Liu ZHOU.
Application Number | 20170191887 15/325622 |
Document ID | / |
Family ID | 53499016 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170191887 |
Kind Code |
A1 |
YANG; Tiehong ; et
al. |
July 6, 2017 |
APPARATUS AND METHOD FOR MEASURING RESIDUAL TORSIONS
Abstract
An apparatus (100, 200, 300) and a method for measuring residual
torsions of an elongated structure (202) such as a steel cord use a
pivot head (102). The pivot head (102) comprises a wheel (104)
adapted to guide an elongated structure (202). The wheel (104) is
mounted in the pivot head (102) to transmit torques exercised by
the elongated structure (202) on the wheel (104) to the pivot head
(102). The pivot head (102) is mounted along a pivotal axis (110).
This pivotal axis (110) lies in a plane of the wheel (104) and
comprises the centre of the wheel (104). Sensor means (116, 206)
measure the torque on the pivot head (102). The pivotal movement of
the pivot head (102) around the pivotal axis (110) is limited to an
angle range of .+-.5.degree., preferably .+-.3.degree. in order to
reach an improved accuracy of the torque measurement.
Inventors: |
YANG; Tiehong; (Jiangsu,
CN) ; YU; Zhigao; (Jiangsu, CN) ; ZHOU;
Liu; (Jiangsu, CN) ; GU; Lei; (Jiangsu,
CN) ; SHEN; Wei; (Jiangsu, CN) ; VANLANDEGHEM;
Bart; (Kruishoutem, BE) ; GOMMERS; Tom; (Gent,
BE) ; VEREECKEN; Erwin; (Kalken, BE) ;
DOORNAERT; Ghislain; (Puntarenas, OSA Peninsula,
CR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NV Bekaert SA |
Zwevegem |
|
BE |
|
|
Assignee: |
NV Bekaert SA
Zwevegem
BE
|
Family ID: |
53499016 |
Appl. No.: |
15/325622 |
Filed: |
July 2, 2015 |
PCT Filed: |
July 2, 2015 |
PCT NO: |
PCT/EP2015/065103 |
371 Date: |
January 11, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01L 5/0047 20130101;
G01L 5/108 20130101 |
International
Class: |
G01L 5/00 20060101
G01L005/00; G01L 5/10 20060101 G01L005/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2014 |
CN |
PCT/CN2014/085699 |
Claims
1. An apparatus for measuring residual torsions of an elongated
structure such as a steel cord, said apparatus comprising a pivot
head, said pivot head comprising a wheel adapted to guide an
elongated structure, said wheel mounted in said pivot head so as to
transmit torques exercised by said elongated structure on said
wheel to said pivot head, said pivot head being mounted along a
pivotal axis in said apparatus, said pivotal axis lying in a plane
of said wheel and comprising the centre of said wheel, said
apparatus further comprising sensor means for measuring torque on
said pivot head caused by said elongated structure, wherein said
pivotal movement of said pivot head around said pivotal axis is
limited to an angle range of .+-.5.degree., preferably
.+-.3.degree..
2. The apparatus according to claim 1, said sensor means having a
torque range of .+-.50 N.mm with an accuracy of 0.5% over the full
torque range.
3. The apparatus according to claim 2, wherein said sensor means
have a torque range of .+-.10 N.mm with an accuracy of 0.5% over
the full torque range.
4. The apparatus according to claim 1, wherein said sensor means
measure torque directly by measuring either a torque or a
force.
5. The apparatus according to claim 4, wherein said sensor means
comprises a strain gauge.
6. The apparatus according to claim 4, wherein said sensor means
comprises a torsion spring.
7. The apparatus according to claim 6, wherein said torsion spring
is a double torsion spring.
8. The apparatus according to claim 1, wherein said sensor means
measure torque indirectly by measuring angle or position.
9. The apparatus according to claim 1, wherein said sensor means
has been pre-calibrated to directly show measurement results in
residual torsions per unit of length.
10. A method for measuring residual torsions on an elongated member
such as a steel cord, said method comprising the following steps:
a. mounting a wheel in a pivot head so that any torques exercised
on said wheel are transmitted to said pivot head; b. mounting said
pivot head along a pivotal axis in a frame, said pivotal axis lying
in a plane of said wheel and comprising the centre of said wheel;
c. guiding an elongated member over said wheel; d. measuring torque
generated by said elongated member on said wheel and pivot head
thereby limiting the pivotal movement of said pivot head to
.+-.5.degree., preferably .+-.3.degree..
11. The method according to claim 10, wherein step d. is carried
out by sensor means having a torque range of .+-.50 N.mm with an
accuracy of 0.5% over the full torque range.
Description
TECHNICAL FIELD
[0001] The invention relates to an apparatus and method for
measuring residual torsions on an elongated element such as a steel
cord.
BACKGROUND ART
[0002] Residual torsions on an elongated element such as a steel
cord must be controlled and thus measured during the manufacture of
the elongated element. In the absence of adequate control, the
downstream processing of the elongated elements such as the
integration of steel cords into rubber plies may become difficult
or even problematic. Indeed, uncontrolled residual torsions of
steel cords may give rise to tip rise of rubber sheets reinforced
with those steel cords. The automatic handling of those rubber
sheets may fail as a result of this tip rise.
[0003] The prior art discloses several embodiments to measure
residual torsions.
[0004] U.S. Pat. No. 4,642,979 discloses a way of adjusting the lay
of a wire rope by measuring the remaining or residual torque in the
wire rope. After the twisting of the wire rope, the wire rope is
running in a U-portion over a wheel or dancer roller. This dancer
roller is pivotally mounted. The angle of rotation of the dancer
roller is measured in order to have an indication about the
remaining torque on the wire rope.
[0005] This method of measuring residual torsions by measuring the
rotation angle of a dancer roller that may pivot more or less
freely, although widely used in practice, has several
disadvantages.
[0006] When allowing the dancer roller to rotate freely, one starts
to influence the parameter one want to measure, namely the free
rotation starts to reduce already the number of residual
torsions.
[0007] In addition, the measurement shows some hysteresis
behaviour.
[0008] Moreover, practice has shown that it is difficult to cover
the full range of residual torsions, despite the possibility for
almost free rotation.
DISCLOSURE OF INVENTION
[0009] It is an object of the invention to avoid or at least to
mitigate the drawbacks of the prior art.
[0010] It is a further object of the invention to provide simple
means to measure residual torsions.
[0011] It is another object of the invention to provide measurement
means that are more accurate.
[0012] It is still another object of the invention to provide
measurement of residual torsions over the whole range.
[0013] Yet another object of the invention is to increase the range
of residual torsions that may be measured.
[0014] According to a first aspect of the invention, there is
provided an apparatus for measuring residual torsions of an
elongated structure such as a steel cord. The apparatus comprises a
pivot head. The pivot head comprises a wheel adapted to guide an
elongated structure. This wheel is mounted in the pivot head so as
to transmit torques exercised by the elongated structure on the
wheel to the pivot head.
[0015] The pivot head is mounted along a pivotal axis in the
apparatus. The pivotal axis of the pivot head lies in a plane of
the wheel and comprises the centre of the wheel.
[0016] The apparatus further comprises sensor means for measuring
torque on the pivot head caused by the elongated structure.
[0017] The pivotal movement of the torsion head around the pivotal
axis is limited to an angle range of .+-.5.degree., preferably to
.+-.3.degree., most preferably limited to an angle range of
.+-.2.degree..
[0018] The terms `elongated member` not only refer to a steel cord
but also to other twisted or untwisted structures such as a metal
strand, a wire rope, a twisted single wire, . . .
[0019] By reducing the amplitude range of rotation of the pivot
head to a very small range, the negative influence of the rotation
itself on the residual torsion measurement is also reduced to a
very small portion.
[0020] The reduced amplitude range also facilitates the covering of
the whole range of residual torsions and, as will be explained
hereinafter, even enlarges the range of residual torsions that can
be measured.
[0021] One of the preferred embodiments is to have a 0.degree.
rotation of the pivot head.
[0022] The amplitude of rotation of the pivot head may be reduced
by integrating into the mechanical chain from wheel to frame a
stiff element such as a stiff torsion spring and/or a stiff load
cell of the sensor means itself. Following Hooke's law, these stiff
elements translate a great torque into a small displacement.
[0023] An additional advantage of using very stiff elements is
that--next to a more accurate measurement--the measurable torque
range, and thus the measurable range of residual torsions, may be
increased as well.
[0024] The sensor means preferably have a torque range of .+-.50
N.mm with an accuracy of 0.5% over the full torque range. Most
preferably, the sensor means have a torque range of .+-.10 N.mm
with an accuracy of 0.5% over the full torque range.
[0025] With this type of sensors a high accuracy is reached over a
torque range which covers the whole range of residual torsions met
in practice.
[0026] The sensor means preferably measure torque directly by
measuring torque or force.
[0027] In one embodiment of the invention, the sensor means may
comprise a strain gauge or strain gauges as load cell.
[0028] In another embodiment of the invention, the sensor means may
comprise a torsion spring, e.g. a double torsion spring, as load
cell.
[0029] The sensor means may also measure torque indirectly by
measuring distance, position or angle.
[0030] Most preferably the sensor means is pre-calibrated in order
to directly show measurement results in number of residual torsions
per unit of length.
[0031] By calibrating the sensor means in advance per cord
construction and prior to install the sensor means in production,
calibration in situ can be prevented or at least reduced to a
minimum.
[0032] According to a second aspect of the invention, there is
provided a method for measuring residual torsions on an elongated
member such as a steel cord. The method comprises the following
steps: [0033] a) mounting a wheel in a pivot head so that any
torques exercised on the wheel are transmitted to said pivot head;
[0034] b) mounting the pivot head along a pivotal axis in a frame,
where the pivotal axis lies in a plane of the wheel and comprises
the centre of the wheel; [0035] c) guiding an elongated member over
the wheel; [0036] d) measuring torque generated by the elongated
member on the wheel and pivot head thereby limiting the pivotal
movement of the pivot head to .+-.5.degree., preferably to
.+-.3.degree..
[0037] Preferably step d) is carried out by sensor means having a
torque range of .+-.50 N.mm with an accuracy of 0.5% over the full
torque range, most preferably by sensor means having a torque range
of .+-.10 N.mm with an accuracy of 0.5% over the full range.
BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS
[0038] FIG. 1a and FIG. 1b show a first embodiment of an apparatus
for measuring residual torsions according to the invention.
[0039] FIG. 2 shows a second embodiment of an apparatus for
measuring residual torsions according to the invention.
[0040] FIG. 3 shows a third embodiment of an apparatus for
measuring residual torsions according to the invention.
Mode(s) for Carrying Out the Invention
[0041] FIGS. 1a, 1b and FIG. 2 illustrate ways of direct
measurement of the torque.
[0042] FIG. 1a is a cross-section of a first embodiment of an
apparatus 100 for measuring residual torsions according to plane AA
of FIG. 1b. FIG. 1b is a cross-section of this apparatus 100
according to plane BB of FIG. 1a.
[0043] Apparatus 100 has a pivot head 102. A wheel or pulley 104 is
mounted in this pivot head 102 on an axle 106 via a bearing 108.
The wheel 104 can rotate freely around the axle 106. The axle 106
is fixed on the pivot head 102. The pivot head 102 together with
the wheel 104 is rotatably mounted along a pivot axis 110. Thereto
pivot head 102 is mounted via suspension springs 112 in a frame
114. The suspension springs 112 are preferably rather flexible
springs with a relatively low spring constant to allow rotating the
pivot head 102 as freely as possible. The suspension springs 112
may be formed by a thin steel wire. The mechanical chain from pivot
head 102 to frame 114 also comprises stiff elements in the form of
strain gauges 116. These stiff elements take up the major part of
the torque and limit the rotation of the pivot head 102 to
.+-.3.degree., preferably to .+-.2.degree.. Preferably strain
gauges 116 are selected with a high accuracy and high gauge
factor.
[0044] Alternatively, stiff suspension springs 112 with a high
spring constant may be used and put in series with the strain
gauges 116. Relatively thick wires may form these stiff suspension
springs 112. In contrast to FIG. 1a, a mechanical link is made
between one of the suspension springs and the strain gauges 116.
This embodiment has the advantage that the whole torque range is
not taken up by the strain gauges only.
[0045] Still another alternative is to use the same set up as FIG.
1a with a type of parallel arrangement between the suspension
springs 112 and the strain gauges 116. The alternative lies in the
use of stiff suspension springs 112 instead of flexible suspension
springs. The ratio of torque taken up by the suspension springs 112
to the torque taken up by the strain gauges 116 is calibrated.
[0046] FIG. 2 shows yet another apparatus 200 for measuring
residual torsions on an elongated member 202.
[0047] A steel cord 202 makes a type of U-form around a wheel 104
that is connected to a pivot head 102. Pivot head 102 is rotatably
mounted along pivot axis 110.
[0048] Pivot head 102 is connected by means of a stiff suspension
spring 204 to a static torque sensor 206. The static torque sensor
206 may be of a commercially existing type. Such a torque sensor
may comprise strain gauges inside that are mechanically connected
to the torsion bar. Any torque exercised by the suspension spring
204 deforms the torsion bar and, as it does so, also elastically
and reversibly deforms the strain gauges that are fitted to the
torsion bar. The changes of electrical resistance of the strain
gauges are proportional to the deformation of the strain
gauges.
[0049] Preferably the torque sensor may have four strain gauges. A
multiple of four strain gauges may also be used. These strain
gauges are arranged as a Wheatstone bridge circuit and are supplied
with DC voltage or with AC voltage or with AC current by the sensor
via connection 208. The output voltage from the strain gauges is
proportional to the measured torque. The use of AC allows
elimination of the thermal offset and thermocouple effects in the
system. Static torque sensor 206 may be housed in a frame 210.
[0050] FIG. 3 illustrates a way of indirect measurement of the
torque on pivot head 102.
[0051] Pivot head 102 with wheel 104 is rotatably hung by means of
a suspension spring 302 to a frame 304. The mechanical chain
between pivot head 102 and frame 304 comprises a double torsion
spring 306', 306''. In case the torsion constant of the double
torsion spring 306', 306'' is high, the torsion constant of the
suspension spring 302 may be somewhat lower. In case the torsion
constant of the double torsion spring 306', 306'' is low, the
torsion constant of the suspension spring 306, 306'' is higher. The
total mechanical chain must be stiff enough to limit the rotation
of the pivot head 102 to .+-.3.degree..
[0052] Preferably the suspension spring 302 is flexible and the
double torsion spring 306', 306'' stiff so that the main part of
the torque is taken up by the double torsion spring 306',
306''.
[0053] A left arm 308' and a right arm 308'' are connected to the
pivot head 302.
[0054] In case pivot head 302 rotates in the direction of arrow
310', left arm 308' moves a little bit the trailing end of the left
part 306' of the double torsion spring.
[0055] In case pivot head 302 rotates in the direction of arrow
310'', right arm 308'' moves a little bit the trailing end of the
right part 306'' of the double torsion spring.
[0056] The degree of displacement of the trailing ends of the
double torsion spring 306', 306'' or the amount of displacement of
the arms 308', 308'' is proportional to the torque exercised on the
wheel 104 and to the amount of residual torsions present on the
elongated member.
LIST OF REFERENCE NUMBERS
[0057] 100 first embodiment of measurement apparatus [0058] 102
pivot head [0059] 104 wheel or pulley [0060] 106 axle [0061] 108
bearing [0062] 110 pivot axis [0063] 112 suspension spring [0064]
114 frame [0065] 116 strain gauge [0066] 200 second embodiment of
measurement apparatus [0067] 202 elongated member [0068] 204
suspension spring [0069] 206 torque sensor [0070] 208 connection
cable [0071] 210 frame [0072] 300 third embodiment of measurement
apparatus [0073] 302 suspension spring [0074] 304 frame [0075] 306'
left part of double torsion spring [0076] 306'' right part of
double torsion spring [0077] 308' left part of arm [0078] 308''
right part of arm [0079] 310' direction of rotation where left part
of double torsion spring is touched [0080] 310'' direction of
rotation where right part of double torsion spring is touched
* * * * *